Re: Hairpin with text inside

[David Kastrup]

Rutger Hofman <address@hidden> writes:

>> Can you run this in a debugger so that one can get a backtrace and see
>> where the defective indexing actually occurs?  Then it should be
>> possible to code an explicit behavior there.
>>
>
> Right.
>
> My lilypond is built without debugging symbols. It is full of:
> #4  0x000000000040e1c0 in ?? ()
> etc etc, no useful lilypond frames (there is a meaningful frame in
> assert.c:101).
>
> Do you still want the backtrace?

I looked at your example code and, well, it would be pointless to get a
backtrace here.  Sorry, I had assumed that you set some argument in some
LilyPond call to CENTER and caught LilyPond on the wrong foot.  If I had
looked more closely, I would not have asked for a backtrace which really
could not tell a better story than your original post.

You actually explicitly and manually call the Scheme function

               (ly:stencil-combine-at-edge
                 (ly:stencil-aligned-to stencil X RIGHT)
                 Y CENTER
                 ; Y DOWN
                 (ly:stencil-aligned-to (grob-interpret-markup grob text) X 
RIGHT))

and that's just meaningless.  There is no thing like a "center" edge.
The documentation string is clear here:

 -- Function: ly:stencil-combine-at-edge first axis direction second
          padding
     Construct a stencil by putting SECOND next to FIRST.  AXIS can be 0
     (x-axis) or 1 (y-axis).  DIRECTION can be -1 (left or down) or 1
     (right or up).  The stencils are juxtaposed with PADDING as extra
     space.  FIRST and SECOND may also be ‘'()’ or ‘#f’.

and it would be meaningless to apply padding when you just want to
superimpose two stencils.  This rather sounds like you want to use
ly:stencil-add on the stencils, just combining them on the same
reference point.

I don't think there is _any_ point in letting ly:stencil-combine-at-edge
accept CENTER as the direction since I cannot think of anything useful
to do with the padding then: in which direction would one be supposed to
shift the second stencil when it overlapped the first one?

-- 
David Kastrup